// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_BASE_UPLOAD_FILE_ELEMENT_READER_H_
#define NET_BASE_UPLOAD_FILE_ELEMENT_READER_H_

#include <stdint.h>

#include <memory>

#include "base/compiler_specific.h"
#include "base/files/file.h"
#include "base/files/file_path.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "net/base/net_export.h"
#include "net/base/upload_element_reader.h"

namespace base {
class TaskRunner;
}

namespace net {

class FileStream;

// An UploadElementReader implementation for file.
class NET_EXPORT UploadFileElementReader : public UploadElementReader {
public:
    // |task_runner| is used to perform file operations. It must not be NULL.
    UploadFileElementReader(base::TaskRunner* task_runner,
        const base::FilePath& path,
        uint64_t range_offset,
        uint64_t range_length,
        const base::Time& expected_modification_time);
    ~UploadFileElementReader() override;

    const base::FilePath& path() const { return path_; }
    uint64_t range_offset() const { return range_offset_; }
    uint64_t range_length() const { return range_length_; }
    const base::Time& expected_modification_time() const
    {
        return expected_modification_time_;
    }

    // UploadElementReader overrides:
    const UploadFileElementReader* AsFileReader() const override;
    int Init(const CompletionCallback& callback) override;
    uint64_t GetContentLength() const override;
    uint64_t BytesRemaining() const override;
    int Read(IOBuffer* buf,
        int buf_length,
        const CompletionCallback& callback) override;

private:
    FRIEND_TEST_ALL_PREFIXES(ElementsUploadDataStreamTest, FileSmallerThanLength);
    FRIEND_TEST_ALL_PREFIXES(HttpNetworkTransactionTest,
        UploadFileSmallerThanLength);

    // Resets this instance to the uninitialized state.
    void Reset();

    // These methods are used to implement Init().
    void OnOpenCompleted(const CompletionCallback& callback, int result);
    void OnSeekCompleted(const CompletionCallback& callback, int64_t result);
    void OnGetFileInfoCompleted(const CompletionCallback& callback,
        base::File::Info* file_info,
        bool result);

    // This method is used to implement Read().
    int OnReadCompleted(const CompletionCallback& callback, int result);

    // Sets an value to override the result for GetContentLength().
    // Used for tests.
    struct NET_EXPORT_PRIVATE ScopedOverridingContentLengthForTests {
        explicit ScopedOverridingContentLengthForTests(uint64_t value);
        ~ScopedOverridingContentLengthForTests();
    };

    scoped_refptr<base::TaskRunner> task_runner_;
    const base::FilePath path_;
    const uint64_t range_offset_;
    const uint64_t range_length_;
    const base::Time expected_modification_time_;
    std::unique_ptr<FileStream> file_stream_;
    uint64_t content_length_;
    uint64_t bytes_remaining_;
    base::WeakPtrFactory<UploadFileElementReader> weak_ptr_factory_;

    DISALLOW_COPY_AND_ASSIGN(UploadFileElementReader);
};

} // namespace net

#endif // NET_BASE_UPLOAD_FILE_ELEMENT_READER_H_
